RNS Discussion with Dr. King-Stephens (Part 5)

Part 5 of my RNS discussion with Dr. King-Stephens:

The RNS is able to detect brain activity that could indicate a seizure. How does it know the difference between normal activity and seizure activity?

The physician decides what is normal and abnormal for that individual. By looking at a number of records of brain activity from that patient, the physician can identify the specific patterns that characterize that person’s seizures. The device is then programmed by the physician to detect those specific patterns. Thus, the device is programmed differently for each individual.

If the RNS is able to distinguish between different types of brain activity it is essentially reading your mind. Can it detect emotional responses?

The RNS detects the brainwave activity but does not "read the mind". It would probably take a supercomputer with millions of electrodes placed over every cell in the brain in order to be able to "read" peoples thoughts. After all, the mind is the expression of all the brain cells activity at any given time.

For what other purposes is the RNS technology being used?

Right now, the RNS is only being used in a clinical trial for refractory epilepsy. It may be used for other conditions in the future.

Previous Posts (Part 1 Part 2 Part 3 Part 4)

If you have epilepsy and are interested in finding out if you are a good match for the RNS clinical study, Call: 1-866-904-6630 or go to: www.seizurestudy.com

RNS Discussion with Dr. King-Stephens (Part 4)

Part 4 of my RNS discussion with Dr. King-Stephens:

How does the RNS “know” to send an electrical pulse to the brain?

The RNS uses very sophisticated computer programs to recognize abnormal brain electrical activity and distinguish it from normal activity. The data (or EEG) is stored in the RNS and by communicating with a laptop computer, similar to a heart pacemaker, it can be retrieved and sent to a computer at NeuroPace and stored for future review.

Once the patient downloads the activity that is stored in the device to the main computer at NeuroPace, the doctors can review it and make changes in the detection programs to improve the ability of the device to recognize the seizure activity. The better the device gets at distinguishing the abnormal from normal brain activity, the better it works at blocking the seizures and improving the control of the epilepsy.

The RNS must acquire a significant amount of data about your brain. How is that data stored and how is it sent to your physician?

The data is stored on servers and is password protected, that is, the physician can access the information only for his or her own patients.

The pulse of a VNS has to be powerful enough to reach the activation threshold of the Vagus nerve and cause it to “fire”. How powerful do RNS pulses have to be in order to interrupt seizure activity in the brain?

The magnitude of the electrical activity delivered to the brain to control the seizures is much lower with RNS than VNS, (probably around 15% of what is needed for VNS). Since there are no pain nerve fibers in the brain, the patient does not feel the "shock" applied by the device.

Previous Posts (Part 1 Part 2 Part 3)
More tommorow.

If you have epilepsy and are interested in finding out if you are a good match for the RNS clinical study, Call: 1-866-904-6630 or go to: www.seizurestudy.com

RNS Discussion with Dr. King-Stephens (Part 3)

Part 3 of my RNS discussion with Dr. King-Stephens:

The VNS has a number of possible side-effects, the main one being that it affects your voice. What are some possible side effects that you have already discovered during your studies?

Some patients have had mild tingling and/or pain of the scalp or face but by reducing the intensity of the stimulation or repositioning the electrodes, the symptoms disappear. So far, the side-effect profile has been excellent, i.e. few side-effects, and the patients do not have any sensation when the brain is receiving the therapy, which averages about 600 very brief pulses a day!!!

One of the things that most concerned me when deciding to get a VNS is the whole concept of being a Cyborg: Part man – part machine. The RNS seems to be more invasive and more “cyborgish”. How would you address these concerns to potential study participants?

The RNS in no way can change the personality of the person or "take over" their feelings or thoughts because it is only stimulation; less than 1% of their brain. There is no chance of becoming the "Terminal Man".

If you had epilepsy, what treatments would you try before electing to have a RNS implant?

If I had epilepsy, I would try at least 2 medications, alone or in combination, before looking at the possibility of having "curative" surgery. If I was not a candidate for curative surgery but could have the RNS, I would go for it. If not a candidate for surgery or RNS, then I would try VNS or an investigational medication.

Previous Posts (Part 1 Part 2)
More tommorow.

If you have epilepsy and are interested in finding out if you are a good match for the RNS clinical study, Call: 1-866-904-6630 or go to: www.seizurestudy.com

RNS Discussion with Dr. King-Stephens (Part 2)

Part 2 of my RNS discussion with Dr. King-Stephens:

I have generalized tonic-clonic seizures. My EEG shows that the electrical activity does not start at one point in the brain and spread, but occurs on both sides of the brain at once. Would I be a good candidate for an RNS?

At this time, only patients who have focal onset seizures, 1 or 2 foci, are candidates for the study. It might be that in the future, people with generalized seizure onsets might be candidates for this therapy.

The VNS has been around since the nineties and has been implanted in over 30,000 patients. It is well studied and effective for many people. Why would I want to consider an RNS as opposed to the VNS?

VNS is indicated for patient in whom we do not know where the seizures are coming from, have more than 2 foci or have generalized onset seizures. Thus, the indications for using VNS or RNS are very different at this time.

How do you find the specific point on the brain at which to place RNS leads? Is an EEG or regular MRI sufficient?

In order to determine where the seizures are originating in the brain, we do EEG, MRI and occasionally PET studies. If the non-invasive studies can not give us the answer, we sometimes introduce (implant) the EEG electrodes into or placed on the surface of the brain, to capture the seizures and investigate whether we can find the focus or foci. This requires a surgical procedure and observation in the hospital for 7 to 10 days.

Once you have received a VNS, Cyberonics recommends that you not have any further MRIs as the strong magnetic field could heat up the leads wrapping around the Vagus nerve. As an MRI is required to determine the locations to place RNS leads, could a person with a VNS have an RNS implanted?

A person with a RNS generally should not have a MRI scan of the brain because the device creates so much artifact that the information given by the scan is often useless. Also, the MRI may cause heating of the leads. If an imaging procedure is necessary, x-ray based technologies such as a CT scan should be used whenever possible. Hopefully, future RNS devices will be MRI compatible.

The study website indicates that the leads & electrodes are implanted in the brain and that the neurotransmitter is placed in the skull. When you say “in the skull”, does that mean in the cavity with the brain or under the scalp?

The device is embedded in the skull and does not go into the brain. It is then covered by the muscle, fat and scalp and is therefore not visible. The EEG electrodes do go into and/or sit on the surface of the brain and therefore are under the skull.

Previous Posts (Part 1)
More tommorow...

If you have epilepsy and are interested in finding out if you are a good match for the RNS clinical study, Call: 1-866-904-6630 or go to: www.seizurestudy.com

RNS Discussion with Dr. King-Stephens (Part 1)

I recently had the opportunity to candidly speak with Dr. King Stephens about the Responsive Neurostimulator (RNS), a new treatment for epilepsy that is currently in clinical trials. Dr. King-Stephens is the Director of Clinical Neurophysiology at the California Pacific Medical Center in San Francisco.

(As the discussion was quite long, I'll split the transcript into 5 posts.)

Neurology is probably the most complex of all sciences. The amount we know about the brain is far outweighed by the amount we still have to learn. So what in the world possessed you to go into neurology? Surely you could have chosen something more lucrative and less frustrating… like podiatry or plastic surgery?

My interest in neurology is due to the complexity of the brain. Every patient is challenging and keeps the work interesting. Having the opportunity to do research and take care of patients is a privilege and rewarding when we can improve someone's life.

How much have you been involved with the development of the RNS?

I was not involved in the preclinical development of RNS but have worked in the clinical study for almost 2 years.

Experiments with direct neurostimulation and neuro-feedback to the brain have been going on for many years now. What technology specific to the RNS has moved the device to the point where you think it will be practical as an implant.

Improvement in the microprocessors (smaller size and increased speed), reduction in the size of the battery and specially in the algorithms that help recognize the seizure activity have made possible the development of this device.

I had brain surgery about 15 years ago to remove some tissue that was hemorrhaging on my brain and was causing simple-partial seizures. The surgery involved opening a hole the size of a playing card in order to remove the tissue. I had to stay in the hospital for 5 days! What size hole is required for the RNS leads to be placed? And have brain surgery techniques advanced much in the last 15 years?

The size of the (burr) hole to implant the electrodes is about the size of a quarter. The opening of the bone for embedding the RNS device is about 1 x 1/2 x 1/4 of an inch. The advancement in surgical techniques has involved better and safer anesthesia medications, MRI studies during or after surgery and post-operative care.

More tommorow.

If you have epilepsy and are interested in finding out if you are a good match for the RNS clinical study, Call: 1-866-904-6630 or go to: www.seizurestudy.com